netem: fix classful handling
Commit 10f6dfcfde (Revert "sch_netem: Remove classful functionality")
reintroduced classful functionality to netem, but broke basic netem
behavior :
netem uses an t(ime)fifo queue, and store timestamps in skb->cb[]
If qdisc is changed, time constraints are not respected and other qdisc
can destroy skb->cb[] and block netem at dequeue time.
Fix this by always using internal tfifo, and optionally attach a child
qdisc to netem (or a tree of qdiscs)
Example of use :
DEV=eth3
tc qdisc del dev $DEV root
tc qdisc add dev $DEV root handle 30: est 1sec 8sec netem delay 20ms 10ms
tc qdisc add dev $DEV handle 40:0 parent 30:0 tbf \
burst 20480 limit 20480 mtu 1514 rate 32000bps
qdisc netem 30: root refcnt 18 limit 1000 delay 20.0ms 10.0ms
Sent 190792 bytes 413 pkt (dropped 0, overlimits 0 requeues 0)
rate 18416bit 3pps backlog 0b 0p requeues 0
qdisc tbf 40: parent 30: rate 256000bit burst 20Kb/8 mpu 0b lat 0us
Sent 190792 bytes 413 pkt (dropped 6, overlimits 10 requeues 0)
backlog 0b 5p requeues 0
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
David S. Miller
Родитель
32b293a53d
Коммит
50612537e9
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@ -67,7 +67,11 @@
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*/
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struct netem_sched_data {
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/* internal t(ime)fifo qdisc uses sch->q and sch->limit */
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/* optional qdisc for classful handling (NULL at netem init) */
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struct Qdisc *qdisc;
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struct qdisc_watchdog watchdog;
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psched_tdiff_t latency;
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@ -117,7 +121,9 @@ struct netem_sched_data {
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};
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/* Time stamp put into socket buffer control block */
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/* Time stamp put into socket buffer control block
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* Only valid when skbs are in our internal t(ime)fifo queue.
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*/
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struct netem_skb_cb {
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psched_time_t time_to_send;
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};
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@ -324,6 +330,31 @@ static psched_time_t packet_len_2_sched_time(unsigned int len, struct netem_sche
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return PSCHED_NS2TICKS(ticks);
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}
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static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
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{
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struct sk_buff_head *list = &sch->q;
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psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
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struct sk_buff *skb;
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if (likely(skb_queue_len(list) < sch->limit)) {
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skb = skb_peek_tail(list);
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/* Optimize for add at tail */
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if (likely(!skb || tnext >= netem_skb_cb(skb)->time_to_send))
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return qdisc_enqueue_tail(nskb, sch);
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skb_queue_reverse_walk(list, skb) {
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if (tnext >= netem_skb_cb(skb)->time_to_send)
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break;
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}
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__skb_queue_after(list, skb, nskb);
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sch->qstats.backlog += qdisc_pkt_len(nskb);
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return NET_XMIT_SUCCESS;
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}
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return qdisc_reshape_fail(nskb, sch);
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}
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/*
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* Insert one skb into qdisc.
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* Note: parent depends on return value to account for queue length.
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@ -399,7 +430,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
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now = psched_get_time();
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if (q->rate) {
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struct sk_buff_head *list = &q->qdisc->q;
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struct sk_buff_head *list = &sch->q;
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delay += packet_len_2_sched_time(skb->len, q);
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@ -417,7 +448,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
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cb->time_to_send = now + delay;
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++q->counter;
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ret = qdisc_enqueue(skb, q->qdisc);
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ret = tfifo_enqueue(skb, sch);
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} else {
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/*
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* Do re-ordering by putting one out of N packets at the front
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@ -426,7 +457,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
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cb->time_to_send = psched_get_time();
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q->counter = 0;
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__skb_queue_head(&q->qdisc->q, skb);
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__skb_queue_head(&sch->q, skb);
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q->qdisc->qstats.backlog += qdisc_pkt_len(skb);
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q->qdisc->qstats.requeues++;
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ret = NET_XMIT_SUCCESS;
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@ -439,19 +470,20 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
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}
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}
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sch->q.qlen++;
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return NET_XMIT_SUCCESS;
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}
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static unsigned int netem_drop(struct Qdisc *sch)
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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unsigned int len = 0;
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unsigned int len;
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if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) {
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sch->q.qlen--;
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len = qdisc_queue_drop(sch);
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if (!len && q->qdisc && q->qdisc->ops->drop)
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len = q->qdisc->ops->drop(q->qdisc);
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if (len)
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sch->qstats.drops++;
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}
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return len;
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}
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@ -463,16 +495,16 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
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if (qdisc_is_throttled(sch))
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return NULL;
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skb = q->qdisc->ops->peek(q->qdisc);
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tfifo_dequeue:
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skb = qdisc_peek_head(sch);
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if (skb) {
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const struct netem_skb_cb *cb = netem_skb_cb(skb);
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psched_time_t now = psched_get_time();
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/* if more time remaining? */
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if (cb->time_to_send <= now) {
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skb = qdisc_dequeue_peeked(q->qdisc);
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if (cb->time_to_send <= psched_get_time()) {
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skb = qdisc_dequeue_tail(sch);
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if (unlikely(!skb))
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return NULL;
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goto qdisc_dequeue;
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#ifdef CONFIG_NET_CLS_ACT
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/*
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@ -483,15 +515,37 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
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skb->tstamp.tv64 = 0;
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#endif
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sch->q.qlen--;
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if (q->qdisc) {
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int err = qdisc_enqueue(skb, q->qdisc);
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if (unlikely(err != NET_XMIT_SUCCESS)) {
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if (net_xmit_drop_count(err)) {
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sch->qstats.drops++;
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qdisc_tree_decrease_qlen(sch, 1);
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}
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}
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goto tfifo_dequeue;
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}
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deliver:
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qdisc_unthrottled(sch);
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qdisc_bstats_update(sch, skb);
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return skb;
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}
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if (q->qdisc) {
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skb = q->qdisc->ops->dequeue(q->qdisc);
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if (skb)
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goto deliver;
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}
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qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send);
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}
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qdisc_dequeue:
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if (q->qdisc) {
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skb = q->qdisc->ops->dequeue(q->qdisc);
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if (skb)
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goto deliver;
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}
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return NULL;
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}
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@ -499,8 +553,9 @@ static void netem_reset(struct Qdisc *sch)
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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qdisc_reset(q->qdisc);
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sch->q.qlen = 0;
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qdisc_reset_queue(sch);
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if (q->qdisc)
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qdisc_reset(q->qdisc);
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qdisc_watchdog_cancel(&q->watchdog);
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}
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@ -690,11 +745,7 @@ static int netem_change(struct Qdisc *sch, struct nlattr *opt)
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if (ret < 0)
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return ret;
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ret = fifo_set_limit(q->qdisc, qopt->limit);
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if (ret) {
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pr_info("netem: can't set fifo limit\n");
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return ret;
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}
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sch->limit = qopt->limit;
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q->latency = qopt->latency;
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q->jitter = qopt->jitter;
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@ -735,88 +786,6 @@ static int netem_change(struct Qdisc *sch, struct nlattr *opt)
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return ret;
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}
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/*
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* Special case version of FIFO queue for use by netem.
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* It queues in order based on timestamps in skb's
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*/
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struct fifo_sched_data {
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u32 limit;
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psched_time_t oldest;
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};
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static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
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{
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struct fifo_sched_data *q = qdisc_priv(sch);
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struct sk_buff_head *list = &sch->q;
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psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
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struct sk_buff *skb;
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if (likely(skb_queue_len(list) < q->limit)) {
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/* Optimize for add at tail */
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if (likely(skb_queue_empty(list) || tnext >= q->oldest)) {
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q->oldest = tnext;
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return qdisc_enqueue_tail(nskb, sch);
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}
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skb_queue_reverse_walk(list, skb) {
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const struct netem_skb_cb *cb = netem_skb_cb(skb);
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if (tnext >= cb->time_to_send)
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break;
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}
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__skb_queue_after(list, skb, nskb);
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sch->qstats.backlog += qdisc_pkt_len(nskb);
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return NET_XMIT_SUCCESS;
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}
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return qdisc_reshape_fail(nskb, sch);
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}
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static int tfifo_init(struct Qdisc *sch, struct nlattr *opt)
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{
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struct fifo_sched_data *q = qdisc_priv(sch);
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if (opt) {
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struct tc_fifo_qopt *ctl = nla_data(opt);
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if (nla_len(opt) < sizeof(*ctl))
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return -EINVAL;
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q->limit = ctl->limit;
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} else
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q->limit = max_t(u32, qdisc_dev(sch)->tx_queue_len, 1);
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q->oldest = PSCHED_PASTPERFECT;
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return 0;
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}
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static int tfifo_dump(struct Qdisc *sch, struct sk_buff *skb)
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{
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struct fifo_sched_data *q = qdisc_priv(sch);
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struct tc_fifo_qopt opt = { .limit = q->limit };
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NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
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return skb->len;
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nla_put_failure:
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return -1;
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}
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static struct Qdisc_ops tfifo_qdisc_ops __read_mostly = {
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.id = "tfifo",
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.priv_size = sizeof(struct fifo_sched_data),
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.enqueue = tfifo_enqueue,
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.dequeue = qdisc_dequeue_head,
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.peek = qdisc_peek_head,
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.drop = qdisc_queue_drop,
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.init = tfifo_init,
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.reset = qdisc_reset_queue,
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.change = tfifo_init,
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.dump = tfifo_dump,
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};
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static int netem_init(struct Qdisc *sch, struct nlattr *opt)
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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@ -828,18 +797,9 @@ static int netem_init(struct Qdisc *sch, struct nlattr *opt)
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qdisc_watchdog_init(&q->watchdog, sch);
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q->loss_model = CLG_RANDOM;
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q->qdisc = qdisc_create_dflt(sch->dev_queue, &tfifo_qdisc_ops,
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TC_H_MAKE(sch->handle, 1));
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if (!q->qdisc) {
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pr_notice("netem: qdisc create tfifo qdisc failed\n");
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return -ENOMEM;
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}
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ret = netem_change(sch, opt);
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if (ret) {
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if (ret)
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pr_info("netem: change failed\n");
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qdisc_destroy(q->qdisc);
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}
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return ret;
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}
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@ -848,7 +808,8 @@ static void netem_destroy(struct Qdisc *sch)
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struct netem_sched_data *q = qdisc_priv(sch);
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qdisc_watchdog_cancel(&q->watchdog);
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qdisc_destroy(q->qdisc);
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if (q->qdisc)
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qdisc_destroy(q->qdisc);
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dist_free(q->delay_dist);
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}
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@ -952,7 +913,7 @@ static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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if (cl != 1) /* only one class */
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if (cl != 1 || !q->qdisc) /* only one class */
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return -ENOENT;
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tcm->tcm_handle |= TC_H_MIN(1);
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@ -966,14 +927,13 @@ static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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if (new == NULL)
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new = &noop_qdisc;
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sch_tree_lock(sch);
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*old = q->qdisc;
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q->qdisc = new;
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qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
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qdisc_reset(*old);
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if (*old) {
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qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
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qdisc_reset(*old);
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}
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sch_tree_unlock(sch);
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return 0;
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